Revealing cytokine-induced changes in the extracellular matrix with secondary ion mass spectrometry

AbstractCell-secreted matrices (CSMs), where extracellular matrix (ECM) deposited by monolayer cell cultures is decellularized, have been increasingly used to produce surfaces that may be reseeded with cells. Such surfaces are useful to help us understand cell–ECM interactions in a microenvironment closer to the in vivo situation than synthetic substrates with adsorbed proteins. We describe the production of CSMs from mouse primary osteoblasts (mPObs) exposed to cytokine challenge during matrix secretion, mimicking in vivo inflammatory environments. Time-of-flight secondary ion mass spectrometry data revealed that CSMs with cytokine challenge at day 7 or 12 of culture can be chemically distinguished from one another and from untreated CSM using multivariate analysis. Comparison of the differences with reference spectra from adsorbed protein mixtures points towards cytokine challenge resulting in a decrease in collagen content. This is supported by immunocytochemical and histological staining, demonstrating a 44% loss of collagen mass and a 32% loss in collagen I coverage. CSM surfaces demonstrate greater cell adhesion than adsorbed ECM proteins. When mPObs were reseeded onto cytokine-challenged CSMs they exhibited reduced adhesion and elongated morphology compared to untreated CSMs. Such changes may direct subsequent cell fate and function, and provide insights into pathological responses at sites of inflammation

Biomaterials Approaches to Combating Oral Biofilms and Dental Disease

Background: Possibilities for biomaterials to impact the dental caries epidemic are reviewed with emphasis placed on novel delivery biomaterials and new therapeutic targets

The impact of detergents on the tissue decellularization process: a ToF-SIMS study

Biologic scaffolds are derived from mammalian tissues, which must be decellularized to remove cellular antigens that would otherwise incite an adverse immune response. Although widely used clinically, the optimum balance between cell removal and the disruption of matrix architecture and surface ligand landscape remains a considerable challenge. Here we describe the use of time of flight secondary ion mass spectroscopy (ToF-SIMS) to provide sensitive, molecular specific, localized analysis of detergent decellularized biologic scaffolds. We detected residual detergent fragments, specifically from Triton X-100, sodium deoxycholate and sodium dodecyl sulphate (SDS) in decellularized scaffolds; increased SDS concentrations from 0.1% to 1.0% increased both the intensity of SDS fragments and adverse cell outcomes. We also identified cellular remnants, by detecting phosphate and phosphocholine ions in PAA and CHAPS decellularized scaffolds. The present study demonstrates ToF-SIMS is not only a powerful tool for characterization of biologic scaffold surface molecular functionality, but also enables sensitive assessment of decellularization efficacy

The Nanoscale Biointerface and Healing Biomaterials

Buddy Ratner of the University of Washington Engineering, Biomaterials Center presented a lecture on October 3, 2002 at 11:00 am in the Suddath Seminar Room, IBB Building, Georgia Tech Campus.Implantable medical devices, and the biomaterials that comprise them, are measured on macro scales (centimeters). Yet the biocompatibility of such devices may be dictated by phenomena best described at nanometer dimensions. Biomedical implants and the University of Washington Engineered Biomaterials (UWEB) Engineering Research Center will be introduced. The classical definition of biocompatibility will be contrasted to a newer definition embracing nanomolecular concepts. Biological data on the in vivo healing responses of mammals to matricellular proteins such as osteopontin, thrombospondin 2 and SPARC will be presented with an emphasis on exploiting the special reactivity of such proteins. First, non-specific protein adsorption must be inhibited. Strategies to achieve this design parameter will be presented. Then methods to deliver the specific protein signals will be addressed. An imprinting approach and a self-assembly approach will be described. Finally, speculation on how such materials that precisely control interfacial biological reactions will be used in medicine will complete this lecture. Modern surface analysis techniques that can address the complexity of a functional biointerface will be highlighted to define nanostructures

Biomaterials science : an introduction to materials in medicine / edited by Buddy D. Ratner ... [et al.]

Includes bibliographical references and index.liii, 1519 p. :The revised edition of this renowned and bestselling title is the most comprehensive single text on all aspects of biomaterials science. It provides a balanced, insightful approach to both the learning of the science and technology of biomaterials and acts as the key reference for practitioners who are involved in the applications of materials in medicine

Levofloxacin impregnation and extended release: Concentration model for insulin catheters

Increasing the lifetime of percutaneous insulin delivery catheters to minimize painful needle sticks increases the risk of infection. To combat surface-adherent bacteria and potential biofilm formation, we developed a method to impregnate levofloxacin antibiotic into the outer polymer of the catheter so that it can leach into the external medium. Complementarily, we developed a method to quantify the concentration of antibiotic to ensure the minimum inhibitory concentration (MIC) is maintained throughout the duration of catheter use. Additionally, we have investigated the extent of antibiotic resistance after a zwitterionic nonfouling coating treatment to ensure suitable release after further surface modification. Levofloxacin was incorporated into the catheter through the swelling of the outer polyurethane of the bilayer catheter and subsequent solvent evaporation. The zone of inhibition was measured over time with S. epidermidis on LB agar plates. The release of levofloxacin was measured using optical absorbance spectroscopy in water and quantified against a linear standard curve at 292 nm. We developed a model using Fick's second law of diffusion to calculate the concentration around the catheter. Visible inhibition of bacterial growth and biofilm formation was shown for up to 38 days. A total of 8–45 µg of antibiotic was released over 26 days and a concentration of 820,000 µg/mL in the 0.17 µL control volume was reached at day 26 for the minimally-loaded samples, an amount many orders of magnitude greater than the MIC. After the nonfouling treatment, the lowest concentration reached was 16 µg/mL after 26 days. In conclusion, we have demonstrated a suitable method to induce antibacterial activity for insulin catheters, maintain the MIC, and sustain antibacterial character following further surface coatings